Bluetooth: ISO: Modify cc in bt_iso_chan_path

The CC/Codec Configuration in bt_iso_chan_path was
defined as an array of size 0. This meant that the
CC always had to be allocated right after the
bt_iso_chan_path struct.

This does not give a very flexible API, and also makes
it impossible for two bt_iso_chan_path to share the same
CC.

The API is modified so that the CC is simply a pointer
to a an array now.

Signed-off-by: Emil Gydesen <emil.gydesen@nordicsemi.no>